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Isolation And Characterization Of Auxin Producing Bacterial Strains From Plant Rhizosphere

by Kanwal Aziz | Dr. Jawad Nazir | Dr | Prof. Dr. Tahir Yaqub.

Material type: book Book; Format: print ; Literary form: drama Publisher: 2013Dissertation note: Auxins are a class of plant hormones or plant growth substances. Auxins have a cardinal role in the regulation of many growth and developmental processes in the plant. Soil samples were serially diluted and screened for auxin production by Salkowski method. Isolates that have the ability to produce auxin were identified by culture characters, morphology, and bio-chemical profile. From 150 isolates, 04 bacteria were selected (AUX-36, AUX-53, AUX-137, and AUX-142). The bacteria were identified by following the flowcharts described in “Berges Mannual of Determinative Bacteriology”, 9th addition. These isolates were identified as Bacillus megaterium, Escherichia coli, Klebsiella pneumonia and Bacillus marinus respectively. Next, different physical and chemical parameters for growth of bacteria and auxin biosynthesis were optimized. For the optimization of bacterial growth OD values of the culture broth (at wavelength 600nm) was taken by spectrophotometer. To estimate the amount of auxin (ìg/ml) produced in the culture broth; a standard curve (concentration of auxin ìg/ml at x-axis and OD value at y-axis) was prepared by using commercially available auxin. The optimum conditions for growth and auxin production by AUX-36 was found to be pH 7, 0.98% osmotic pressure at 37 °C after 72 hours of incubation. If the medium is supplemented with 0.1 and 1.0% glucose, sucrose and peptone then it increased the bacterial growth which ultimately increased the auxin concentration in the broth medium. The growth and auxin Production by AUX-53 was 0.98% NaCl concentration at 37 °C after 72 hours of incubation. The optimum pH was found to be 7 but it showed good growth at acidic as well as alkaline pH. The addition of glucose and sucrose in the growth medium increased the growth as well as auxin production. The optimum conditions for the growth of AUX-137 were as follows: pH=7, 0.98% osmotic pressure, temperature 37 °C. However the isolate had good growth at 28 °C and 2% NaCl concentration as well. The bacterial cell density and auxin increased with incubation time up to 72 hours. The isolate produced highest concentration of auxin under the same conditions. Similarly, the cell density and auxin increased with the increasing concentration of glucose in the growth medium. Sucrose increased the auxin only in the culture filtrate. While the bacteria AUX-142 showed highest growth as well as auxin production at 42 °C after 72 hours of incubation. The optimum pH and osmotic pressure was found to be 7 and 2% respectively. The cell density and concentration of auxin increased with the increasing concentration of peptone in the growth medium. Addition of tryptophan (1-2%) increased the auxin concentration in the culture supernatant of all isolates. Next, the seed germination test and plant pot experiment were performed of selected isolates to observe the effect of bacterial inoculation on wheat plants. In seed germination test treatment of seeds with AUX-36, AUX-53 and AUX-142 significantly increased the root length and number of root hairs as compared to non-treated seeds. In plant pot experiment comparison of various growth parameters of inoculated plants with non-inoculated plants revealed the improvement in plant growth by bacterial inoculation. Availability: Items available for loan: UVAS Library [Call number: 1684,T] (1).

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Efficacy Of Surface Disinfectants Against Bacterial Pathogens On Experimentally Contaminated Pathogens

by Sana Ahmed (2009-VA-241) | Dr. Jawad Nazir | Dr. Amir Ghafoor | Prof. Dr. Tahir Yaqub.

Material type: book Book; Literary form: not fiction Publisher: 2015Dissertation note: Surface disinfection plays a key role in the prevention, control and reduction of many communicable infections as contaminated surfaces are the major source for transmission of microorganisms. Five types of surface cleaning products (Astonish Germ Clear, Cif Floor Cleaner, Dettol Surface Cleaner, Finis Floor Cleaner and Lysol Surface Cleaner) were evaluated for antibacterial activity against three bacterial cultures (E. coli, K. pneumonia, S. aureus) through Quantitative non-porous Surface Carrier Test derived from EN 13697. Efficacy testing was performed through surface contamination techniques. Glass slides surfaces were artificially contaminated followed by recovery of the bacteria through vortex method both before and after the application of product for 5 minutes. Each of the experiment was repeated thrice and microbicidal effect (ME) values after the application of each product were calculated. Residual antimicrobial activity of the surface cleaning products was measured by applying the working solution of disinfectant on contaminated glass surfaces. Exposure time was given to the test surfaces, after each set exposure time the surfaces were treated to recover the microorganisms. Viable count from the eluant was calculated by serial dilution spread plate method. Each of the experiment was repeated thrice to find out the residual antimicrobial effect of the disinfectant products. ME values of the Finis Floor Cleaner ranged from 4.03 to 5.14, which was the maximum value among all surface cleaning products used against E. coli. Highest ME value against S. aureus and K. pneumonia was shown by Astonish Germ Clear. The ME values ranged from 4.99 to 5.10 against S. aureus and 5.34 to 6.99 against K. pneumoniae. Finis Floor Cleaner was proved to be of maximum efficiency against E. coli where as Astonish Germ Clear was most effective against Staph. aureus and K. pneumonia. The mean log10 CFU values recovered from disinfectant treated Summary 49 surfaces when they were exposed to the environment for different time periods of five minutes, six hours and 24 hours are 5.62 to 7.94, 4.17 to 6.35 and 7.16 to 10.25 respectively. The results indicated that the microbial count was reduced significantly at interaction time of five minutes, then at six hours the count was further reduced by Astonish Germ Clear, Cif Floor Cleaner and Dettol Surface Cleaner i.e. these surface cleaners were able to maintain their antimicrobial activity upto six hours. When the exposure to environment further increased to 24 hours, the microbial count started to increase, hence none of the disinfectants has shown antimicrobial activity upto 24 hours. This indicates that significant microbial count can be achieved within the interaction time of five minutes to six hours. Loss of antimicrobial activity upto 24 hours is probably because the active ingredients of cleaning agents get degraded during long interaction time. Present study emphasizes that the surface disinfection process must be repeated at regular intervals. Regular and timely use of surface cleaning agents must be considered as a crucial measure in controlling disease transmission rates. Availability: Items available for loan: UVAS Library [Call number: 2294-T] (1).

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Characterization And Phylogenetic Analysis Of Hemagglutinin Gene Of Avian Influenza Virus Subtype H9n2 Isolated In 2015

by Arslan Mehboob (2009-VA-76) | Prof. Dr. Tahir Yaqub | Dr. Jawad Nazir | Dr. Maryam Javed.

Material type: book Book; Literary form: not fiction Publisher: 2016Dissertation note: H9N2 Avian influenza outbreaks has caused great economic losses to poultry industry resulting in decrease egg production, high morbidity and mortality. Due to different antigenic variants H9 has become problematic. It has the ability to cross species barrier and increase in pathogenicity. Hemagglutination inhibition (HI) test is employed extensively for subtyping and detection of antibody titre against the virus. Continuous mutations in the HA gene transforms AIV subtype H9N2 into more pathogenic virus that may have pandemic potential and can cross species barrier. Thus, it was necessary to identify various antigenic variants of H9 virus. It was important to study the HA gene as it plays vital role in viral attachment, release of genetic material and pathogenicity. In present study, a sum of four H9 virus samples were isolated. Both serological and molecular confirmation was done. 200 samples from different areas were collected and properly labelled. They were then processed for egg inoculation in embryonated eggs. Virus was grown in embryonated eggs and harvested fluid is then proceeded for confirmatory testing. Haemagllutination and Haemagllutination Inhibition testing was done. RNA was extracted by Kit method and cDNA was synthesized. Reverse Transcriptase (RT-PCR) was performed using specific primer sets and then the amplicon were run on agarose gel. The bands obtained was sent for sequencing and Phylogenetic analysis was obtained using software and tree was constructed. Protein analysis was also performed. The present study enabled us to characterize and construct Phylogenetic tree of HA gene of currently prevailing H9N2 Avian Influenza isolates in Pakistan. Availability: Items available for loan: UVAS Library [Call number: 2474-T] (1).

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